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filth may, under certain conditions, actually generate fever, without the entrance of any such fresh agent as a 'specific cause" from without; but between being "highly probable," and "as certain as that two and two make four," there is a good deal of difference. The fact is, that the question of the spontaneous generation of fevers is, like the yet larger question of the spontaneous generation of organic living forms, still a moot point, though it cannot be said in this, as in the larger question, that the "Panspermist" has the weight of authority on his side. In a thickly-populated country like ours, it must always be possible for the seeds of any disease to be carried any whither; and a "Panspermist" ought not to be less vigilant in rooting up what, on his view, would be the necessary nidus for his germs, than the man who believes, as we incline to believe, that the "nidus" itself can produce the eggs. The question, therefore, is not necessarily a practical one; there are diseases enough which have their parentage referred, by all but bad landlords, to bad drainage, and with Dr. Parkes's well-balanced statement of the case we close it. At p. 28 he says, "To sum up: the diseases produced by focal emanations on the general population seem to be diarrhoea; bilious disorders, often with febrile symptoms; dyspepsia; general malaise and anemia-all these being affections of digestion or sanguification; typhoid fever also is intimately connected with sewage emanations, either being their direct result, or, more probably, being caused by specific products being mixed with the sewage. In addition, sewer-air aggravates most decidedly the severity of all the exanthemata, erysipelas, hospital gangrene, and puerperal fever, and probably has an injurious effect on all other cases." On the other hand, recent inquiries have shown that certain so-called "facts" alleged by the anti-sanitarians are, in reality, no facts at all. It has been said by these lovers of darkness, that workmen in sewers are not more subject to fevers than other labourers; but on close analysis it has been shown-first, that these men really are less healthy than their brother operatives; and, secondly, that no account had been taken in the examination and enumeration of healthy sewer-men of the protecting influence which previous unrecorded or unrecognized attacks of fever had conferred upon them; and, lastly, that no set-off had been allowed for the working of natural selection, in weeding-out, at their very first entrance upon the employment, of such would-be sewer-men as had no innate aptitude for the function.

There is a fault of minor importance, in a scientific point of view, but still of much practical moment, into which several sanitarians have fallen, and which all would do well henceforward to avoid. This fault is a fault of style, and consists in the introduction of rhetorical language, of far-fetched metaphors, and even of sacred names into the somewhat earthy matters of which we have been

writing. The man of science recognizes such merit as the evidence may possess, in spite of the masquerading dress it wears-the man of business is prone to turn a deaf ear to it altogether, because of this disguise and disfigurement. The former looks upon such an exhibition as something analogous to the aberrations of form which under certain circumstances beset the crystallization of certain salts, and the grotesqueness of the form assumed blinds him in neither case to the real nature of the substance before him. It is the sweeping style just now mentioned to which he objects, as he judges by sense and not by sound, whereas it is the stilted style which is an abomination to the chairman of a Parliamentary Committee, and may cost the cause which is advocated in it his help, his influence, and his vote.

IV. ON THE ANTIQUITY OF THE VOLCANOS OF AUVERGNE.

By CHARLES DAUBENY, M.D., F.R.S., Professor of Botany at the University of Oxford. (Illustrated.)

ACCUSTOMED, as we are, from our earliest infancy to have the first elementary truths of astronomy instilled into our minds, we can scarcely realize the idea, that nations, even in an advanced state of mental progress, were in the habit of viewing our relations to the celestial bodies around us in quite a different light from that in which they present themselves to us at the present time.

Almost every child who has had a few months' instruction in a parish school knows, that the earth turns round the sun, that the circle which bounds our horizon is not the limit of the universe, that the moon revolves in an orbit, which, although unapproachable by us from its distance alone, is near in comparison with the space which divides us from the sun, and yet that this great luminary is placed, as it were, within our own immediate neighbourhood, as compared with the distance which separates us from even the nearest of the fixed stars.

But these persuasions have grown up within a very recent period, and are due to the slow infiltration of philosophic truths into the minds of the vulgar, gradually displacing the earlier notions which had been acquired through the apparent testimony of our

senses.

In the most flourishing periods of ancient Greece and Rome, in mediæval times, and even in ages approaching to our own, the same belief did not exist; nor, indeed, was a knowledge on such subjects a part of what the Almighty thought fit to impart by supernatural means to his chosen people.

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Now, when it required so many centuries of research to indoctrinate the public mind in more enlarged ideas as to space, it cannot be a matter of surprise that geology, a science of much more recent date than astronomy, should not yet have succeeded in instilling more correct notions as to the extent of past time.

Without going back to times when this science was so much in its infancy, and was so little listened to out of doors, that the great body of the laity, as well as of the clergy, imagined the earth, as well as all the other celestial bodies, to have been called into existence by the direct fiat of the Almighty within the space of six literal days; and when it was taken for granted that the period which had elapsed since the creation of the universe was comprehended within the 6,000 years which, according to Archbishop Usher's calculations, had elapsed since the birth of Adam, I can myself recollect when geologists of reputation, whilst contending that the days of creation must have embraced an extended duration, rather than a compass merely of twenty-four hours, took it for granted, nevertheless, that the latest epoch in the history of our planet-namely, that during which the climate and configuration of the earth's surface corresponded in its general features with those it exhibits at presentwas ushered in by the appearance of man upon the globe, and consequently could not be traced back to an earlier date than that which on Scripture authority had been assigned for the first introduction of our species.

Upon the subject of man's antiquity I shall not enter; but with regard to that of the earth itself I may remark, that subsequent investigations have compelled us to enlarge very materially the allowance of time formerly allotted for its formation. They have shown us at least that if what is called the post-pleiocene epoch is to be estimated as dating its commencement from the setting in of that intense cold which characterizes what is called the glacial period, if to a temperature such as allowed of the growth of subtropical plants had succeeded in the same latitudes as those of our own island, one as rigorous as that of Labrador at present, and if afterwards a gradual change supervened, by which the climate came by degrees to be assimilated to what we experience at present, a longer interval must be supposed, than our received systems of chronology, built upon the assumption that man was a denizen of the earth throughout the whole of that period, would allow us to recognize.

And yet the time taken up in this the latest of the world's stages of progress, if I may so express myself, may bear no larger proportion to that occupied by the whole series of formations from the first dawn of organic life upon the globe to the present time, than the distance in space between us and the moon bears to that which intervenes between our planet and the sun; just as even the time taken up by the deposition of all the rock formations, collectively considered, shrinks as much into insignificance by the side of

that required, according to the computation of mathematicians, for the cooling down of the earth from its original vaporous or incandescent condition, to a temperature such as admitted of the existence of life, as the distance between ourselves and the sun does to that which divides this luminary from the nearest of the fixed stars.

I have been led to these general remarks by the subject which has been proposed for the present communication, in which it will be attempted to show that the phenomena presented by the extinct volcanos of Auvergne tend in a very marked manner to corroborate the inferences which, on other grounds, I have deduced with regard to the long space of time that must have been consumed even by that one stage in the earth's history which connects itself most nearly with the present, not to speak of that almost interminable series of antecedent deposits which contribute to make up the entire crust of the globe.

In order to render this subject more intelligible, it will be necessary for me to enter into some details, which may appear to some rather egotistical, as they will involve an account of my earliest visit to Auvergne, which took place in 1819, before any other British geologist, since the peace with France, had explored the district.

I had come at that time fresh from the lecture-room of Professor Jameson, of Edinburgh, who was regarded a great authority in Geology, partly from the accurate knowledge he possessed of the characteristics of rocks and minerals, and partly as being one of the very few of our countrymen who had studied under Werner, the great Freyburg Professor, whose opinions respecting the structure and formation of the globe gave the law at that time to all who had studied under him.

Although in the lore which he had imported from his German master there was no small admixture of hypothesis, and that, as we now conceive, of a very crude and gratuitous character, yet the Professor contrived to impress his pupils with a high idea of the soundness of his instructions, not only for the reasons already assigned, but also from his dry and didactic manner, which seemed to preclude the notion of anything like fancy or imagination intermingling in the circle of his ideas. Coming forward indeed as the British representative of the Wernerian School of Geology, he felt it incumbent upon him in his lectures to exhibit the greatest possible antagonism to the treatises of Hutton, Playfair, and others of his countrymen who had appealed to Vulcan and Pluto as the main Artificers in the formation of the globe. With this view he founded, in opposition to the Royal Society of Edinburgh, where the Huttonian theory maintained its ascendancy, a new one, consisting chiefly of his own friends and adherents, which was denominated the Wernerian; and in order to render more patent the contrast between his mode of teaching and that of his opponents, he adopted the term Geognosy instead of that of Geology, by way of implying that his views were based upon observation, whilst theirs had drawn largely from the regions of imagination.

Now Werner had carried the Neptunian theory, as it was called, to such an extent, as to regard as deposited from aqueous solution, not only granite, but even basalt and traps of every form and description; and inasmuch as in Saxony from whence his observations were chiefly derived, the trappean rocks occur in vast tabular masses overlying the other strata, he imagined the former to have been deposited in consequence of a great inroad over the land, of water, carrying with it in solution the materials of which these rocks consist, so that the retiring flood left behind it on the summits of the highest ground it had reached those great deposits of trap which are found at this elevation.

And Werner's disciple, Professor Jameson, so far conformed to the creed of his master, that he stoutly maintained the aqueous origin also of all those formations of trap and porphyry which assume such gigantic proportions in various parts of Scotland, in the Hebrides, and in the north of Ireland.

In spite of the striking contrast which these rocks in their lithological characters present to ordinary deposits from water; in spite of the resemblance they bear to the products of fire; in spite of their intrusion into other strata in a manner which conveyed the idea of their former liquidity; and in spite even of the changes they often appear to have wrought upon the beds in contact, indicative, as it would seem, of fusion, Professor Jameson persuaded his pupils that the Wernerian theory was to be extended to them as well as to the rest.

But Auvergne, a region which had been already explored by